..They may be chance findings. Alternatively, given the very low concentrations of SO(2) that were present in Vancouver, SO(2) may have been serving as a surrogate measure of other environmental or meteorological factors...

..5) concentrations from a fixed monitor yielded a much weaker estimate of 1.0% (95% CI: 0.0-2.0% decrease). Relatively small amounts of personal monitor data were needed to calibrate the estimate based on fixed outdoor concentrations...

A study of health effect estimates using competing methods to model personal exposures to ambient PM2.5

..Few studies have prospectively followed panels of urban children with asthma to determine whether air pollution levels are associated with clinically relevant outcomes such as asthma exacerbations...

..We conclude that after accounting for either current level of FEV1 or Schwachman-Kulczycki scores, no other physiological or clinical measures contribute to predicting limitation in a work or school environment...